Downhole depth measuring apparatus

ABSTRACT

According to an aspect of an embodiment, provided is a downhole depth measuring apparatus. The downhole depth measuring apparatus comprises a frame, a cable reel rotatably supported upon the frame, a length of cable carried upon the cable reel, and a level wind assembly supported on the frame for level distribution of the cable on the cable reel during retrieval of the cable. The level wind assembly is operably coupled to a stationary counter assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/431,503 filed Dec. 8, 2016, the contents of which are incorporated herein in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to the field of groundwater monitoring, and in particular to a mechanism for determining accurate cable draw and return.

BACKGROUND OF THE DISCLOSURE

Wells are drilled into the earth for a variety of reasons. The ability to effectively and efficiently monitor a wellbore, for example to assess water levels depends on an accurate determination of depth. A variety of instruments are available for water monitoring, but the assessment of depth has its challenges, in particular with portable well monitoring equipment.

Methods to determine well depth are known, and generally include a calibrated sensor configured to mechanically or optically engage the cable. Upon deployment or retrieval of the cable, the sensor engages the cable and provides the operator with an assessment of cable draw. These systems are effective, but can be very sensitive to contamination from the downhole and surrounding environment.

In addition to making an accurate determination of cable draw, portable well monitoring equipment must also be able to manage the length of cable being used. Where there is considerable cable being deployed and retrieved, the level distribution of the cable upon the cable reel, in particular during retrieval can become a major challenge.

Technologies are known to facilitate the wrapping of line (i.e. rope, piping, etc.) upon a receiving reel during a retrieval operation. These ‘level-wind’ systems provide a coordinated winding of the line, but require a reciprocating guide that positions the cable in a defined winding pattern. This reciprocating movement can be problematic, however, to sensors associated therewith.

There is clearly a need for a downhole monitoring system that permits for an accurate determination of cable draw, while also enabling a level distribution of cable upon the cable reel.

SUMMARY OF THE DISCLOSURE

According to an aspect of an embodiment, provided is a downhole depth measuring apparatus. The downhole depth measuring apparatus comprises a frame, a cable reel rotatably supported upon the frame, a length of cable carried upon the cable reel, and a level wind assembly supported on the frame for level distribution of the cable on the cable reel during retrieval of the cable. The level wind assembly is operably coupled to a stationary counter assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages will be apparent from the following description of the disclosure as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the disclosure. The drawings are not to scale.

FIG. 1 is a front perspective view of the downhole depth measuring apparatus according to an embodiment of the disclosure.

FIG. 2 is a rear perspective view of the downhole depth measuring apparatus according to FIG. 1.

FIG. 3 is a front schematic view of the downhole depth measuring apparatus according to FIG. 1, showing the apparatus positioned proximal a borehole.

FIG. 4 is a front perspective view of the downhole depth measuring apparatus according to FIG. 1, with the cable reel removed to highlight the spindle and reel support portion.

FIG. 5 is a side view of the downhole depth measuring apparatus according to FIG. 1.

FIG. 6 is an exploded perspective view of the level wind assembly of the apparatus according to FIG. 1.

FIG. 7 is a top view of the downhole depth measuring apparatus according to FIG. 1

FIG. 8 is an exploded perspective view of the cable count assembly forming part of the level wind assembly of the apparatus according to FIG. 1.

FIG. 9 is a partial perspective view of the level wind assembly of the apparatus according to FIG. 1, with the winder plate removed to highlight components contained therein.

FIG. 10 is a partial perspective view of the level wind assembly of the apparatus according to FIG. 1, with the winder plate and the second plate of the cable count assembly removed to highlight components contained therein.

FIG. 11 is a partial perspective view of the level wind assembly of the apparatus according to FIG. 1, with various components removed to highlight features of the follower and the rail.

FIG. 12 is a partial front view of the cable count wheel forming part of the level wind assembly of the apparatus according to FIG. 1, showing the relationship between the rail and the bearings.

FIG. 13 is a partial perspective view of the level wind assembly of the apparatus according to FIG. 1, highlighting various aspects of the encoder assembly.

DETAILED DESCRIPTION

Specific embodiments of the present disclosure are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and uses of the disclosure. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following

Referring now to FIGS. 1 and 2, shown is a downhole depth measuring apparatus 10 suitable for use in a groundwater monitoring application. The apparatus 10 includes a frame 20, a cable reel 22, a length of cable 24 carried upon the cable reel 22, and a level wind assembly 26 for level distribution of the cable 24 on the cable reel 22 during retrieval of the cable 24.

Having regard to FIG. 3, the apparatus 10 is shown schematically relative to an exemplary downhole environment. As shown, the apparatus 10 is generally positioned proximal a borehole B such that the cable 24 may be vertically deployed directly from the apparatus 10. As will be discussed in greater detail below, an accurate determination of cable draw from the cable reel 22 is used to establish an accurate valuation of water levels, or depth in general, within the downhole environment. The cable 24 may have attached at its terminal end 28 a weight or plunger 30 to facilitate cable draw during deployment. For certain applications, the weight or plunger 30 may be replaced with a monitoring device, for example a groundwater conductivity data logger or a downhole camera. Deployment and retrieval of the cable 24 from the apparatus 10 is generally achieved by way of manual (i.e. hand) rotation of the cable reel 22. It will be appreciated, however, that for certain applications, the apparatus may include a mechanical (i.e. geared) or motorized system to assist and/or facilitate rotation of the cable reel 22.

Referring now to the various views of apparatus 10 shown in FIGS. 1, 2, 4 and 5, the frame 20 operably supports the cable reel 22. The frame 20 is presented as a tubular structure having a handle portion 32, a footing portion 34 including first and second footing members 36, 38 and a reel support portion 40. The reel support portion 40 presents a spindle 42 (shown in FIG. 4 with the cable reel 22 removed for clarity) having an axis A. The cable reel 22 is rotatably supported upon the spindle 42, and may incorporate suitable bushings and/or bearing to facilitate smooth rotation thereon. The frame 20 may additionally include elements (not shown) that permit the frame 20 to be anchored in place during use. The cable reel 22 includes opposing reel flanges 44, 46 and a central cable support 48 (see FIG. 5, shown in dot). The cable 24 is shown as reeled upon the cable support 48 between reel flanges 44, 46.

The level wind assembly 26 is supported upon the frame 20 by a support bracket 50. The support bracket 50 extends outwardly of the frame 20, to permit the cable 24 to drop vertically into the downhole environment. The support bracket 50 may be a separately formed element fixedly attached to the reel support portion 40 of the frame 20, or may be integrally formed with the reel support portion 40 and/or the frame 20.

Referring now to FIGS. 6 and 7, the level wind assembly 26 includes a plurality of cross-rods 52 a, 52 b, 52 c, 52 d (collectively referred to as cross-rods 52) that extend between the support bracket 50 and an opposing winder plate 54, to form a ridged subframe 56 for the level wind assembly 26. The cross-rods 52 are generally arranged in parallel alignment to the axis A of the spindle 42, which in turn is arranged during use to align generally perpendicular to the vertical drop of the cable 24 during deployment/retrieval.

Rotatably mounted between the support bracket 50 and the winder plate 54 is a shaft 58. The shaft 58 includes a set of reversely extending spiral grooves 60, a configuration generally known in the art as a self reversing screw shaft or a diamond lead screw. A first end 62 of the shaft 58 is supported at the support bracket 50 by a first support member 64, while a second end 66 of the shaft 58 is supported at the winder plate 54 by a second support member 68. As shown, the shaft 58 is configured for rotation about an axis parallel to the axis of rotation A. To reduce friction and improve rotational performance, suitable bushings and/or bearings may be used to rotatably mount the first and second ends 62, 66 of the shaft 58 at the respective first and second support members 64, 68. The first and second support members 64, 68 are attached to the respective support bracket 50 and winder plate 54 using a suitable fastener (i.e. threaded fastener) and/or adhesive. In some embodiments, the first and second support members 64, 68 may be integrally formed with the respective support bracket 50 and winder plate 54.

On at least one side, shaft 58 is provided with a shaft sprocket 70 which is rotationally fixed relative to the shaft 58 such that rotation of the shaft sprocket 70 causes corresponding rotation of the shaft 58. In the embodiment shown, the shaft 58 and the shaft sprocket 70 present corresponding keyed surfaces 72 a and 72 b, respectively, to ensure a rotationally fixed relationship. The shaft sprocket 70 additionally cooperates with a first spacer 74 and a second spacer 76, and at least one registration peg 78 that spans therebetween. The at least one registration peg 78 extends through an aperture in the shaft sprocket 70, and is pressfit into receiving apertures provided in each of the first and second spacers 74, 76, therein ensuring fixed relative rotation of the first and second spacers 74, 76 with the shaft sprocket 70. The arrangement may also include a chain guard 80. As shown, the shaft sprocket 70 is located proximal the first end 62 of the shaft 58.

Similarly, the cable reel 22 is provided with a reel sprocket 82. The reel sprocket 82 and the cable reel 22 are coaxial relative to the spindle 42, the reel sprocket 82 being rotationally fixed relative to the cable reel 22 such that rotation of the cable reel 22 causes corresponding rotation of the reel sprocket 82. The reel sprocket 82 is operatively connected to the shaft sprocket 70 using a suitable endless belt member 84. As such, the cable reel 22 is rotationally linked to the shaft 58. Accordingly, rotation of the cable reel 22 imparts a torque upon the shaft 58 through the intermediate driving action of the endless belt member 84 between the reel sprocket 82 and the shaft sprocket 70. In the embodiment shown, the endless belt member 84 is presented in the form of a chain.

Slideably mounted upon the cross-rods 52 is a cable count assembly 86. With reference now to FIGS. 8 to 12, the cable count assembly 86 includes a first plate 88, a second plate 90, and a plurality of cross-connectors 92 that maintain the first and second plates 88, 90 in a spaced-apart relationship. The gap-spacing established between the first and second plates 88, 90 permits for a cable count wheel 94 (see FIG. 10) to be rotatably mounted therebetween, as will be described in greater detail below.

The cable count assembly 86 is mounted upon the cross-rods 52 in a manner that permits reversible lateral movement of the cable count assembly 86 between a first position proximal the support bracket 50 and a second position proximal the winder plate 54. As shown, each of the first and second plates 88, 90 is configured with a plurality of cooperating apertures 96 that align and permit the cable count assembly 86 to slidingly move upon the cross-rods 52. To facilitate smooth lateral movement, a slide element 98 a, 98 b, 98 c, 98 d (collectively slide elements 98) is provided between the first and second plates 88, 90 at each location of the cooperating apertures 96. The slide elements 98 may be provided in the form of a suitable linear bearing or bushing.

The cable count assembly 86 further includes a shaft aperture 100 in each of the first and second plates 88, 90 that align to the shaft 58 and permit the cable count assembly 86 to laterally move relative thereto. The apertures 100 in each of the first and second plates 88, 90 are sized with a diameter that is slightly larger than the outside diameter of the shaft 58, to avoid direct contact therebetween during lateral movement of the cable count assembly 86 upon the cross-rods 52.

Between the first and second plates 88, 90 there is located, proximal the shaft 58, a follower 102 (see FIG. 11). The follower 102 presents a follower blade 104 which engages within one or the other of the two spiral grooves 60 provided on the shaft 58, the follower blade 104 being capable of direction reversal from one of the spiral grooves to the other at the ends of the grooves as known with self reversing screw shafts of this design. A first follower mount 106 a and a second follower mount 106 b are provided, each presenting tabs 108 on each side that mount within a corresponding aperture 110 in each of the first and second plates 88, 90. In this way, the follower 102 remains locked and stationary relative to the first and second plates 88, 90.

Upon rotation of the shaft 58, for example during a cable retrieval operation, the follower 102 fixedly attached between the first and second plates 88, 90 causes lateral movement of the cable count assembly 86 on the cross-rods 52 from one side of the level wind assembly 26 to the other and back. The cable reel 22 is operably connected to the shaft 58 such that the shaft 58 is rotationally linked to the cable reel 22. Accordingly, rotation of the cable reel 22 translates into back and forth (i.e. reciprocating) lateral movement of the level wind assembly 26 upon the cross-rods 52 between the first position proximal the support bracket 50 and the second position proximal the winder plate 54. With this motion of the level wind assembly 26, during a retrieval operation, the cable 24 is directed in a controlled manner along substantially the entire width of the cable reel 22 generally perpendicular to its axis of rotation A.

As mentioned previously, the gap-spacing established between the first and second plates 88, 90 permits for the cable count wheel 94 to be rotatably mounted therebetween. As shown in FIG. 10, the cable count wheel 94 is mounted upon a rotatable rail 112 which extends across the level winder assembly 26. Having regard to FIG. 7, a first end 114 of the rail 112 is supported by the support bracket 50, while a second end 116 of the rail 112 is supported by the winder plate 54. The rotatable rail 112 is aligned to be parallel to the axis of rotation A. The rail 112 extends through a rail aperture 118 provided in each of the first and second plates 88, 90 of the cable count assembly 86. At the winder plate 54, the second end 116 of the rail 112 may be supported in a suitable journal or bearing that permits the rail 112 to freely rotate relative thereto. The first end 114 of the rail 112 extends towards and through the support bracket 50, and into a counter assembly 120 configured to be fixedly mounted on the support bracket 50 of the frame 20. Where the rail 112 extends through the support bracket 50, the rail 112 may be rotationally supported by a suitable bushing or bearing.

The cable count wheel 94 is mounted upon the rail 112 in a manner that permits for a fixed relative rotation of the wheel 94 relative to the rail 112, yet permits the cable count wheel 94 to displace laterally along the rail 112 as the cable count assembly 86 moves laterally upon the cross-rods 52 between the first position proximal the support bracket 50 and the second position proximal the winder plate 54.

The cable count wheel 94 includes a first wheel flange 122, a second wheel flange 124 and a cable engagement portion situated therebetween. The first and second wheel flanges 122, 124 and the cable engagement portion are positioned coaxially relative to the axis of rotation of the rail 112. The cable engagement portion is configured with a reduced diameter compared to the first and second wheel flanges 122, 124, thus presenting a groove 126 that receives and engages the cable 24 during use. In some embodiments, the first and second wheel flanges 122, 124 may be configured to present a cable engagement portion that is a v-groove, to direct the cable 24 to the center thereof.

The rail 112 is configured with at least one planar bearing surface which extends along at least a portion of the length of the rail 112 and which cooperates with a slide element (i.e. a bearing) provided on the cable count wheel 94. With reference to FIGS. 11 and 12, the rail 112 presents three planar bearing surfaces 130 a, 130 b, 130 c (collectively bearing surface 130) that engage a respective bearing 132 a, 132 b, 132 c (collectively bearing 132) mounted in the cable engagement portion of the cable count wheel 94. Each bearing 132 is mounted upon a shaft located in a channel formed into the cable engagement portion. As shown in FIG. 12, bearings 132 a, 132 b, 132 c are mounted on respective bearing shafts 134 a, 134 b, 134 c (collectively bearing shaft 134) seated in respective channels 136 a, 136 b, 136 c (collectively channel 136). For clearance of bearings 132 a, 132 b, 132 c, the cable engagement portion provides respective channels 136 d, 136 e, 136 f. The bearing shafts 134 are positioned in the cable engagement element such that the axis of each bearing shaft 134 is placed in parallel alignment to the plane of a corresponding bearing surface 130 of the rail 112. Specifically, the axes of bearing shafts 134 a, 134 b, 134 c are placed in parallel alignment to the plane defined by bearing surfaces 130 a, 130 b, 130 c, respectively. Accordingly, the bearings 132 mounted upon the respective shafts 134 present a roller surface 138 that engages the respective bearing surface 130 of the rail 112. As shown, roller surfaces 138 a, 138 b, 138 c of respective bearings 132 a, 132 b, 132 c engage respective bearing surfaces 130 a, 130 b, 130 c. The engagement of the bearings 132 with the respective planar bearing surfaces 130 on the rail 112 ensure a fixed relative rotation of the cable count wheel 94 with respect to the rail 112, yet permits for lateral displacement of the cable count wheel 94 relative to the rail 112 as the cable count assembly 86 moves laterally upon the cross-rods 52 between the support bracket 50 and the winder plate 54.

The cable count assembly 86 may additionally include a cable guide presenting a first roller 140 a and a second roller 140 b. The first and second rollers 140 a, 140 b are mounted on respective guide rods 142 a, 142 b mounted between respective guide supports 144 a, 144 b. The guide supports 144 a, 144 b each present a tab 146 on each side thereof, which cooperate with a corresponding slot 148 on each of the first and second plates 88, 90. The first and second rollers 140 a, 140 b are arranged with a gap-spacing therebetween, permitting guided passage of the cable 24 between the cable count wheel 94 and the cable reel 22.

Engagement of the cable 24 within the groove 126 of the cable count wheel 94 serves to rotate the cable count wheel 94 during deployment and retrieval of the cable 24 relative to the cable reel 22. In turn, the engagement of the bearings 132 upon the respective bearing surfaces 130 of the rail 112 serve to transfer the rotation of the cable count wheel 94 to the rail 112.

Rotation of the cable count wheel 94 is dependent upon the engagement and movement of the cable 24 relative thereto. Stated differently, the rotation of the cable count wheel 94 is operably decoupled from the cable reel 22. Although the cable count wheel 94 is mounted on the cable count assembly 86 which moves laterally within the level wind assembly 26, the rotation of the cable count wheel 94 is dependent upon the engagement of the cable count wheel 94 with the cable 24, and not through a direct linkage (i.e. geared) with the cable reel 22.

As mentioned above, the first end 114 of the rail 112 extends towards and through the support bracket 50, and into the counter assembly 120 mounted on the support bracket 50 of the frame 20. With this arrangement, the counter assembly 120 is kept stationary relative to the frame 20, that is it does not move with the level wind assembly during deployment/retrieval of the cable 24. It will be appreciated that a variety of counter assemblies may be suitable used. In the embodiment shown, the counter assembly 120 is provided in the form of a rotary encoder. The rotary encoder is operably connected to the rail 112. As generally known in the art, rotary encoders are used to convert rotational motion of a shaft or axle into an analog or digital signal that may be indicative of a number of parameters, including the angular position of the rail 112. With a calibration of the encoder having regard to the dimension/circumference of the cable count wheel 94, and with a count of the number of rotations of the rail 112 from an initial reference point, an accurate determination can be made of the length of cable 24 deployed and/or retrieved onto the cable reel 22. A variety of rotary encoders may be used for this application including, but not limited to, a mechanical rotary encoder, a magnetic rotary encoder, and an optical rotary encoder.

In the embodiment shown in FIG. 13 (with a rear cover plate removed for clarity), the rotary encoder is presented in the form of an optical rotary encoder 150. The optical rotary encoder 150 includes an encoder disk 152 affixed to the first end 114 of the rail 112. The encoder disk 152 is rotationally fixed relative to the rail 112 such that rotation of the rail 112 causes corresponding rotation of the encoder disk 152. The disk 152 will have a pattern of clear 154 and opaque 156 sections distributed around the disk 152. Where the disk 152 is provided in the form of a metal or opaque plastic disk, the clear sections 154 may be provided as slits 158.

The clear sections 154 (or slits 158) cooperate with a light source 160 and an optical sensor 162, arranged on opposite side of the disk 152. The light source 160 and optical sensor 162 are situated relative to the disk such that the incident light is detected by the optical sensor 162 when the incident light passes through the clear sections 154 (or slits 158). Readings from the optical sensor 162 are analyzed via suitable circuitry (i.e. a processor, not shown), and the resulting output is used to determine positional information for the rail 112. With knowledge of the rotational turn count of the rail 112, combined with the known dimensions of the cable count wheel 94, an accurate determination of the length of cable deployed from an initial reference point can be calculated.

While various embodiments have been described above, it should be understood that they have been presented only as illustrations and examples of the present disclosure, and not by way of limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the disclosure. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. All patents and publications discussed herein are incorporated by reference herein in their entirety. 

1. A downhole depth measuring apparatus, comprising, a frame; a cable reel rotatably supported upon the frame; a length of cable carried upon the cable reel; a level wind assembly supported on the frame for level distribution of the cable on the cable reel during retrieval of the cable; wherein the level wind assembly is operably coupled to a stationary counter assembly.
 2. The apparatus according to claim 1, wherein the level wind assembly includes a cable count assembly supported upon a plurality of cross rods spanning between a support bracket extending from the frame, and an opposing winder plate, the cable count assembly being reversibly laterally moveable between a first position proximal the support bracket, and a second position proximal the winder plate.
 3. The apparatus according to claim 2, wherein the cable count assembly is provided with a slide element at each point of contact with the plurality of cross rods.
 4. The apparatus according to claim 3, wherein the slide elements are provided in the form of a linear bearing.
 5. The apparatus according to claim 2, wherein the cable count assembly includes a follower configured to cooperate with a rotatable shaft mounted between the support bracket and the winder plate, the follower having a follower blade that engages a set of reversely extending spiral grooves provided on the rotatable shaft, therein directing the cable count assembly to move laterally relative thereto.
 6. The apparatus according to claim 5, wherein the rotatable shaft is rotationally linked to the cable reel through the intermediate driving action of an endless belt member interconnecting a shaft sprocket provided on the cable shaft, and a reel sprocket provided on the cable reel.
 7. The apparatus according to claim 2, wherein the level wind assembly includes a rotatable rail extending between the support bracket and the winder plate, the rotatable rail being configured at one end to be coupled to the stationary counter assembly, and further being configured along its length to support a cable count wheel forming part of the cable count assembly, wherein the cable count wheel is mounted upon the rotatable rail in a manner that permits for a fixed relative rotation of the cable count wheel relative to the rotatable rail, yet permitting lateral movement relative thereto.
 8. The apparatus according to claim 7, wherein the rotatable rail is configured with at least one planar bearing surface which engages a corresponding slide element provided on the cable count wheel, therein establishing the fixed relative rotation of the cable count wheel relative to the rail.
 9. The apparatus according to claim 8, wherein the rotatable rail is configured with three planar bearing surfaces, and wherein the slide element corresponding to each planar bearing surface is presented in the form of a bearing.
 10. The apparatus according to claim 9, wherein each bearing presents a roller surface that engages a respective bearing surface on the rotatable rail.
 11. The apparatus according to claim 1, wherein the counter assembly is provided in the form of a rotary encoder.
 12. The apparatus according to claim 11, wherein the rotary encoder is provided in the form of an optical rotary encoder. 